Oscilloscopes For Audio 101 -Part 4B - Push Pull Amplifier Troubleshooting

[@generoley]

Greatest series. Watching you doing actual troubleshooting and hearing your thought process is invaluable information. Thanks.

[@MikeM-Colorado]

I come back to this every once in a while, and learn something new every time. Thanks Mark!

[@Ocean_breezes]

Excellent troubleshooting! Retired EE here and you make a great instructor. Methodical and patient. Im restoring a Pioneer Receiver/ Theater system when I stumbled on your channel.. Brings back memories of bench trouble shooting using the scope. Thank you again!

[@user-ub5su9vj6d]

It really helped, I learned a lot. Thanks so much. Keep on going, we need more video. 👍👍👍🙏🙏🙏

[@chowderheadreynolds7325]

Such a practical session! Who hasn't had their work interrupted by a phone call or something else and missed completing a step? This was better than good!

[@bobkraft9029]

Can't thank you enough, Mark, for taking the time to create these videos. They are incredibly helpful!

[@ikkentonda]

Man! I’m ostensibly an officially certified electrical engineer (albeit in the prior millennium) but I’ve enjoyed (and learned from) every video in this series immensely, this one in particular. I’d have given up a limb or three to have had a few labs taught by you when I was in college!

[@1959Berre]

Very well explained. A missed solder point is a common mistake; it happens to the best of us. (Keeps us humble too). Thank you for the video.

[@fb341]

Excellent series! It's important for us to see more experienced people like you show us that you're not infallible. It reminds us that all of us can make mistakes. Thank you for taking us through that process, Mark.

[@SDsailor7]

This channel is the first one to do an actual tutorial on how to use the O'scope and all the accessories that are required when doing a troubleshooting same as the previous tutorial. All the other YT channels only do the theory on how to use the O'scope so this channel has them beat!

[@FluxCondenser]

I’m glad you made that mistake as it led to one of the better diagnostic videos I’ve ever seen. Well done.

[@neilsheldon8355]

I don't know any person who is absolutely perfect. And if I never made an error in my work, I might think this was hilarious. But if one stops to think of just how many skills are involved in being a good electronics technician, the room for errors grows exponentially. Odds are that someday, every tech will get into some kind of situation where they teach themselves a lesson. The question is if you are willing to learn from it or ignore it. I think it was a great video and it showed an excellent example of troubleshooting a fault down to the level where you can fix it. That, and a humble attitude is what makes a tech great. Thank you for sharing the video.

[@williamsmith5872]

Fantastic video, Mark! I almost jumped out of my chair when you lifted up that resistor. I’ve done that same thing myself. Thanks again.

[@MrBamboocha82]

Most, if not all, of our mistakes, can be excellent learning opportunities. In fact, learning from failure is often the key to success. By getting things wrong, you'll improve your skills and grow in various ways. If you're learning, you won't go wrong. Keep up the good work and thank you so much for the video.

[@paulbrantley5212]

Your candor and openness about the process is much appreciated. Demonstrating the use and limitations of what can be found with test equipment such as a scope, meter and schematics. Thank you, Mark!

[@user-sh9du2nv5y]

Mark this was a fantastic video your humility is a #1 with me I don't think there's one guy out there that hasn't made the same mistake but was even better with the fact that we went from start to finish and how much information was there to learn from.

[@darranbyng3738]

Really enjoyed the series so far.Exactly what i was looking for.Would like to see a video using a solid state unit and digital oscilloscopeThanks so much for taking the time,cheers

[@jasonlamoureux7578]

Even the best and most experienced musicians and performers poop the bed or hit a wrong note now and then.. it would stand to reason that it happens in any and all professions. I thought you reacted with humility and were very humble, the sign of a true professional. Thanks for these O-scope vids, they're fantastic. Cheers from Ontario Canada 🇨🇦

[@weschilton]

Really enjoyed this video! Its so easy in these point to point amps to miss a solder point, especially if interrupted. But what a great troubleshooting process. I learned quite a bit!

[@kennymanchester]

Absolutely excellent series OM! Very nice work on troubleshooting too. I am making the jump to some audio repair and restoration on vintage solid state equipment from RF and general consumer electronics repair. Your series has clarified so many questions for me in that transistion. The practical knowledge transfer has been absolutely amazing. I'm not much of a vacuum tube guy at all, so now with this video out of the way I'm anxious to dig into your solid state troubleshooting content. Best 73, Kenny- NZ5i

[@ItsWesSmithYo]

2023, what happened to part 5? 😂 I’m dying here looking for the audio part 🫶😎🖤🐓

[@allthethingswedo]

And 4C...the solid state troubleshooting, too. I am looking forward to both of those!

[@willrobertson826]

Great video very interesting as you logicly walked thru both channels comparing readings and finding the problem .No shame in a missed solder point .We all learn from stuff like this .just reinforces good build habits the time and aggrevation it takes to find such a little thing is better spent in the build .Great looking amp The console amps are a lot of fun to rebuild

[@bparker86]

Definitely enjoying the heck out of the series and you gained another loyal subscriber. I wanted to add in that I found it very refreshing that you included your own mistakes and let us see that. I gained alot of respect for you when I saw that my friend. Thank you for the great series brother!! God bless

[@bobvines00]

Mark, thank you for sharing "real world" troubleshooting as you found & fixed the problem. I also look forward to the solid-state amp troubleshooting, especially since I have a receiver with one bad channel. I hope to learn enough to find & fix the problem and get stereo back! ;) This is a wonderful, practical series!

[@SDsailor7]

Were you able to find the problem with the bad channel on your receiver?

[@bobvines00]

@@SDsailor7 No, not yet. It hasn't made it that far up my list of projects, especially since it was replaced quite a while ago with a more capable receiver (used to integrate our "modern" entertainment center/cable TV).

[@dwightpollock]

I came a little late to this series of videos. But I have found them to be vary helpful and great content. I would also love to see part 5 if you ever have the time. Thank You very much!!!

[@anithasshenoy6662]

Great trouble shooting. Forgetting to solder / bad solder is normal. It could have been a real open resister too. Finding it is the key. Well demonstrated.

[@Shueysstuff]

Perfect video! Really looking forward to the rest of the video series.

[@gilbus4989]

Another very informative troubleshooting video. Thanks Mark.

[@georgejobin1744]

I'm glad you forgot to solder that resister I learned alot of things because of that. What a awesome video. Thanks mark for that great learning experience. I understood everything you said and did. I love your channel

[@daveunderwood1528]

Another valuable session with a real situation. Thank you so much! Your videos have inspired the dust to be blown off the oscilloscope and multimeter.

[@stevemaas99]

spectacular troubleshooting, and pretty easy to follow along with. what surprises me is how messy a tub amplifier is inside, I'm used to the orderly layouts of solid state equipment.

[@peteleoni9665]

Mark, that was an incredible learning experience. Thank you.

[@barrydraeger1892]

Thanks Mark! We all make mistakes 😉 My first thought was negative feedback issues on the bad channel. It was very educational digging deeper to find the real culprit.

[@W3KW]

Your 2246 looks brand new. I was so impressed with it I thought I’d like to have one. I’ve been searching for a short time and those available all look like they’ve been through a war. Why don’t people take care of their equipment? These things were not cheap new!

[@georgabenthung3282]

Thank's for this Oscilloscopes 101 Videos. I learned a lot of them!

[@x1w2v3]

Thank you all your helpful videos! Oscilloscope for Audio 101 series is great!

[@Frustratedfool]

Another gem of a video. I learn more with every video you produce. My 807SE build had many tiny mistakes, but I’m glad I made them, as I learnt more finding and fixing them (despite your excellent video series, I too managed to miss soldering components and plain getting them in the wrong places too!). The killer was the OPT schematic needing to be reverse polarity when using global feedback - that was a pain to diagnose. I know you mentioned Edcore possibly mislabelling your OPT’s but thought mine would be ok as they were bought much later and would therefore a different batch. But a single sentence in a lengthy blog-post said that when using global feedback, you must always reverse the OPT polarity and the final piece of the puzzle was completed. Just bought a new oscilloscope, and a Function Generator is on order. Will upgrade my 807 to some new MKP caps, check I am getting the best out of the amp, then on to the next build. Thank you.

[@harryhall5092]

Mark, don't feel bad I've done the same thing. I've been working on this stuff for years and it's happened to me more than once. Love your videos and still find good tips you do on these. Electronics is a vast field to be in!

[@sajusebastian4991]

Today watched second time.Really good troubleshooting tips.Thanks.Greetings from Vienna.Austria

[@theguitaramptech]

We've ALL been there. It was still great watching your problem-solving process. Very well done. Thank you.

[@billbates7810]

Really good video Mark, I’ve certainly created my own problems more than once!

[@trainliker100]

Not an idiot for making a mistake. Mistakes are an indication that somebody is actually DOING something. One of mine was spending a long time trying to find out why I was getting so much noise out of a very low noise amplifier I was designing for a pH sensor (using an OP07 op amp). It turns out I had forgotten to turn on the power supply. So, my scope was basically hooked up to a lousy antenna picking up the radiation of the nearby radio station and whatever else was passing by. And on some things with feedback loops, sometimes it is possible to disconnect the feedback and run it open loop making it a little easier to narrow down a trouble area.

[@FredFloresca]

Watching your exercise of troubleshooting was fun and educational. Thank you!

[@restorationsofmusicsystems8609]

Thannk you so musc. Thank you again for the information on what can be done with the oscilloscope I just bought. Great sharing.

[@bobribortone3026]

Great video Mark. Keep them coming.

[@JasonLeaman]

Nothing wrong with making mistakes and admitting to it, the problem is when you pass the blame :P good work sir ! Nice find !

[@hugobloemers4425]

That was cool. I liked this one because it was not staged and trouble shooting a build or restoration is always more difficult than a unit that has been working.

[@imrichmorvay2227]

Mark You told in video "I'm not perfect" but YOU ARE! thanks a lot

[@8507duke]

First rate video, excellent example of real world faulting, thank you!!!!!

[@MultiMathis]

glad you do this ! good lessons :) Thats really exactly what i need for learning ... you know here in Germany its hard to find a channel like this...or someone who teach you person to person :)))

[@preiter20]

Great troubleshooting tips Mark. Thanks for making this video.

[@cat-lw6kq]

Even the best techs make goofs sometimes. This was an excellent training video.

[@dekiriza]

Thanks for amazing content ❤. Do you also have video troubleshooting Solid State amp? I thought part 5 would be it, but can’t locate it

[@amitanaudiophile]

Great to watch this upload, thanks

[@geezberry8889]

not sure if it was mentioned but before any further troubleshooting you should swap the preamp tubes and see if the issue follows the tube

[@DaveyGage]

Good find in the end!

[@plexibreath]

I can't find your Part 5 video. Have you not recorded it yet? I'm looking forward to it I have one of those Rigol scopes and find it confusing as hell so looking forward to seeing it used. I've enjoyed all the other videos in this series, great job!

[@iaov]

Great troubleshooting!! 😊 Thanks

[@billbates7810]

Really good video, excellent!

[@musterionsurly]

Excellent video, thanks.

[@SDsailor7]

Looking forward to part 5A and part 5B

[@Shueysstuff]

Awesome content and awesome presentation! My Scope and function generator just arrived! If there’s a chance the next video could use your Rigol 4 Ch, that would be great!

[@sting1111]

Great video, I learned a great deal.

[@markmckelvey6515]

That was awesome! Thanks for sharing your knowledge and humanity!

[@daviddoty8502]

What happened to part4c and part 5? Cant seem to find them. Great video series.

[@Dave_____]

Thanks for a interesting trouble finding video. I was wondering how you would test for bad capacitors or rule out capacitors causing the issue in the circuit. Perhaps you would have started to check capacitors or the output transformer if all of your resistors would have checked out?

[@noonan1587]

Great video as always Mark. At 40:39 you mention the signal is starting to get 'shaky'. Can you (or anyone here) explain what is causing this? It isn't clipping per say so curious what that is? Thanks!

[@montygore1200]

Fun video. How many times have we all done that

[@valakatz3967]

Thank you Mark, I learn a lot today.

[@msasoundlab1604]

Great and very informative video. I’m planning to getting a scope for audio work. Mostly for troubleshooting/calibrate cassette deck. How should one to connect scope input to cassette deck output? BNC scope input to RCA deck output? Or using probe clip? Thanks in advance

[@rinkerlaw7446]

I have that same scope. Mine has an intermittent problem and I wonder if you have seen it. First off, the scope itself works fine. The problem relates to the Voltmeter and the Cursors. Sometimes, when I press the Voltmeter, the screen says "Ouch. Turn the Volts/Div CCW." At the time, it only displays the top cursor. This occurs even with the Volts/Div fully CCW and with no signal applied. When it is in this mode, the Cursors/Time functionality is also weird. The reference cursor will not extend beyond the center of the screen. I was curious if you had heard of this symptom before. I checked the DC power supplies for levels and they were spot on. I did not check for ripple yet. Though I work on guitar tube amps and other similar gear, I am a little intimidated by the higher voltages found in scopes. I appreciate any input and love your videos. Thanks.

[@paulsto6516]

Fast, but not too fast. Informative, with no fluff. That's tight up there next to awesome!

[@IamChristian777]

Great video , thank you !

[@wbfaulk]

13:07 "The one having the problem is feeding in here on the blue one." 13:20 "We know that the signal coming in on the red line is the one having the problem."

[@edwardhannigan6324]

Nice work Mark.. You need a detention after that..!😂😂 Interesting find and fix..Thanks for sharing..Ed..U.K..😀

[@bob56063]

Looking for video #5 on the solid state amp test. Did I miss it somewhere ?

[@oleghajduk7046]

What generator was used to feed the signal to the amplifier?

[@stevemaas99]

I was looking for part 4C, solid state troubleshooting, did that ever get created?

[@ruudjacobs]

Looking forward to part 4C/5A/5B! Any chance you could give a heads up of when the new episode(s) will be created/released? Thanks so much for this series!

[@bluegrassbanjodude5588]

The way that is wired, without any of the components being on a board of some type.. is that considered point to point?

[@compass504]

Hi Mr. Blue.. Love your Oscope series. I've been searching for a couple of those 8 ohm power resistors. (non inductive). Where did you find them? Ham convention? Thanks for your help. Oh.. 4 years ago I found the same Tek scope you've got. Love it.

[@frustro4323]

#edit# hour and a half later# That is EXACTLY the 2nd place I would have looked. That's wired as triodes right? I'm at 7:56 and I'm gonna take a shot at it. Those EL84's are in a SRPP? config and I'd say it's similar to the knock of an engine with the timing off. The "push pull" are fighting each other at some point. It's probably fixed bias and...well, it's 2 in the morning and I'm just going to finish watching.

[@teijostahl4380]

Best practice is ask someone to check your work. Sometimes we are blind to our mistakes. And first unplug your DUT before making resistance measures. So many burnt ohm-meters! Great tutorial, thanks!

[@Blueglow]

Thats why I power them off and showed everyone to discharge capacitors in the video.

[@teijostahl4380]

Unplugging device under test is a safety measure I use. A short glimpse at loose power socket, ready to start. Forgetting to switch off power, and then grounding caps, gives unpleasant surprise, specially for a beginner. Special grounding rod, you use, is a great idea.

[@kka10001]

Nice video, I like the truth, been there a few times myself. Primo trouble shooting

[@kaleoride]

Very high value content. Thank you for sharing this

[@elicuriel9007]

Great videos but I'm new to electronics and am trying to build up my tool box. I was wondering what you were using to discharge the capacitor. Is that a homemade device or can I buy something like that?

[@MrDoneboy]

Thanks for the video lesson!

[@jjohnson67sg]

How come the capatitors did not discharge themselves? doesn't RC in circuit do this? Thanks Mark

[@junkforlessutube]

Are you still doing a Part 4C on solid state? Thanks.

[@and1424]

hello. what kind of probes do you use? x1? x10? brand? thanks!

[@PaulRichards78]

Hi, when will you be releasing the 5th part in this series ?

[@yosherinferari2631]

Nice Sears audio made by Fisher !!!

[@adaboy4z]

Ive done that on a Restoration not soldering in a capacitor.

[@denouch358]

Very helpful video, I loved it.

[@JImmY1982MinG]

Great video as always, I do have a question though, what signal generator should us beginners get? Assuming we don't use anything crazy but still, any suggestion on the brand or model to pick up? I don't mind use vintage or used, in fact I think the older gears are probably easier to use for a newbie like me..

[@Blueglow]

kzbin.info/www/bejne/rWSVYZegiK5gnas

[@JImmY1982MinG]

@@Blueglow Thank you sir!!!!

[@hksunchaser1]

Good lesson! Thx

[@kgsalvage6306]

As soon as you started and had that distorted signal, I thought that you should disconnect the feedback loop to make sure that it's not causing false readings on the first stage.

[@Blueglow]

Agreed, but then it wouldn't have made for a great oscilloscope video :-)

[@andyfinlay9776]

"I make myself look like an idiot in front of all my loyal viewers here..." Yeah, no. This is a fantastic lesson in fault finding. Working on a vintage AC30, or anything similar with solid (rather than stranded) wires between turrets? This is exactly what happens with these older amps, a wire breaks but appears to be connected causing all sorts of odd issues. And I have lost count of the times that I've found unsoldered legs of components in consumer and professional units over the years, both tube and solid state. Soundcraft analogue mixing consoles? Done loads of those over the years that had EQ and Aux pots not properly soldered in, while still sort of working!

[@merrittderr9708]

You have to hate when that happens, but owning up is the key. Nice find. When you are running these educational videos, some closer attention to the component values would be good. As noted by pi-duino, you made multiple references to the 470k resistors as 470 ohms and made similar references to a couple of other resistors along the way. While some number of us here might be reading the schematic and the DMM and yelling at you, there may be some who are being confused. Just saying . . .

[@James-dt7ky]